Inertial Motion, Explanation, and the Foundations of Classical Spacetime Theories

Abstract

I begin by reviewing some recent work on the status of the geodesic principle in general relativity and the geometrized formulation of Newtonian gravitation. I then turn to the question of whether either of these theories might be said to “explain” inertial motion. I argue that there is a sense in which both theories may be understood to explain inertial motion, but that the sense of “explain” is rather different from what one might have expected. This sense of explanation is connected with a view of theories—I call it the “puzzleball view”—on which the foundations of a physical theory are best understood as a network of mutually interdependent principles and assumptions.

Keywords

General relativity Newtonian gravitation Explanation Inertial motion

This manuscript was prepared in 2012 and has not been significantly revised since then. I still hold the philosophical views defended here, but have not attempted to update the manuscript in light of more recent work by myself or others.

Notes

Acknowledgements

Versions of this work have been presented at CEA-Saclay (Paris), University of Wuppertal, University of Pittsburgh, University of Chicago, University of Texas at Austin, Columbia University, Brown University, New York University, University of Western Ontario (twice!), University of California–Berkeley, University of California–Irvine, Yale University, University of Southern California, Notre Dame University, Ludwig-Maximilians University, and at the ‘New Directions’ conference in Washington, DC. I am grateful to very helpful comments and discussion from all of these audiences, and particularly to (in no special order) John Manchak, Giovanni Valente, Craig Callender, Alexei Grinbaum, Harvey Brown, David Wallace, Chris Smeenk, Wayne Myrvold, Erik Curiel, Ryan Samaroo, John Norton, John Earman, Howard Stein, Mike Tamir, Bryan Roberts, Shelly Kagan, Sahotra Sarkar, Josh Dever, Bob Geroch, Bill Wimsatt, David Albert, Tim Maudlin, Sherri Roush, Josh Schechter, Chris Hill, Don Howard, Katherine Brading, Eleanor Knox, and Radin Dardashti. Special thanks are due to David Malament, Jeff Barrett, Kyle Stanford, and Pen Maddy for many helpful discussions and comments on previous versions of this work. Thank you, too, to Dennis Lehmkuhl for organizing the 2010 workshop on which this volume is based, and for editing the volume.

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